Following the Second Vatican Council (1962–1965), over a thousand priests and religious sisters and brothers were exiled, imprisoned, tortured, or murdered in Latin America by authoritarian governments. A much larger number of lay Church workers were also incarcerated, brutalized, or killed. Most suffered or died because, following the ideals of Vatican II and the Second Latin American Bishops Conference at Medellín, Colombia (1968), they committed themselves to the amelioration of the marginalized in their countries, even though they were fully aware that to do so placed their lives in great peril. This chapter treats a select number—mostly priests and nuns—who were killed because of their prophetic devotion to the poor. It is limited to the nations of Mexico, Brazil, Chile, Argentina, and Central America. It also touches on the bitter divisions that resulted in the Church as a consequence of this new religious activism. Finally, it demonstrates why the deaths of so many religious-based social justice activists forced the institutional Catholic Church to reexamine its outdated criteria for martyrdom.